1. Field of the Invention
The present invention relates to biopsy instruments and, in particular, to a biopsy instrument with which a cored tissue sample can be severed to allow easy retrieval.
2. Description of the Related Art
One of the most frequently used instruments for biopsy, particularly biopsy of the skin, is the so-called Keyes punch. For example, the Baker/Cummins or Baker Biopsy Punch manufactured by a division of Key Pharmaceutical, Miami, Fla.
An example of a conventional punch biopsy instrument 10 is shown in FIG. 1. That instrument has a tubular cutting end 12 formed, for example, from metal and mounted to a plastic handle 14. By advancing the biopsy instrument 10 against the tissue to be sampled, a cylinder of tissue is cored by the razor-sharp beveled circular tip 13. The instrument 10 may be advanced as deep into the tissue as permitted by the length of the metal cylinder, typically by using a gentle pressure combined with a twirling rotation action effected by the practitioner manipulating the handle.
A deficiency of the above-noted instrument is that after the tissue sample has been cored, removal of the cylindrical sample is difficult as the same remains connected to the surrounding tissue at its base. Indeed, currently no device or system has been provided which can advantageously and simply cut the still attached distal segment of tissue. At present, general practice is to use tweezers or the like to pull the exposed end of the tissue core, thus stretching the tissue cylinder. The deepest margin accessible to a surgical blade or scissors is then cut in order to remove the tissue sample from the body of the patient. It is generally not possible to sever the cored tissue sample at its base without cutting the non-cored adjacent tissue.
Thus, the use of the conventional punch biopsy instrument has several disadvantages, including distortion of the major portion of the tissue biopsy from the pulling action of the tweezers or like instrument, which can potentially lead to histological artifacts and incomplete removal of the cored tissue. Indeed, often less than one half of the cored tissue is actually attained in practice. Finally, fragmentation and subdivision of the biopsy with loss of orientation of margins of the fragments is possible.